1. Field of the Invention
This invention relates to high efficiency gas-fired furnaces, and in particular to means for handling condensate formed in the products of combustion therein.
2. Description of the Background Art
Modern furnaces frequently employ a secondary heat exchanger to extract additional heat from the products of combustion and thereby improve the overall efficiency of the furnace. A problem, however, arises in such furnaces as the increased heat extraction causes condensate to form in the products of comubstion at the relatively low discharge temperatures provided by such furnaces. The combustion of conventional hydrocarbon fuels results in the formation of various products of combustion which, when dissolved in the condensate, tend to form acid solutions. Illustratively, natural gas typically includes some sulfur dioxide and sulfur trioxide which, when dissolved in the water vapor condensate, produce weak sulfuric acid. Similarly, carbon dioxide, in the products of combustion, may form a weak carbonic acid.
Notwithstanding the weak characteristics of the acid, it is, in some instances, undesirable to discharge such acidic condensate directly to conventional household drains and the like. One solution to the problem has been to provide means for neutralizing the acidic condensate before discharging it to the drain. An example of such a furnace structure is illustrated in U.S. Pat. No. 4,289,730 of Ronald S. Tomlinson, which patent is owned by the assignee hereof. As shown therein, a neutralizer is mounted within the furnace cabinet for treatment of the acidic condensate and neutralization thereof prior to the delivery thereof from the furnace, such as to the household drain.
A similar structure is illustrated in U.S. Pat. No. 4,309,947 of Edward A. Ketterer, which patent is also owned by the assignee hereof. In this patent, agitation of the neutralizer is effected during operation thereof so as to provide improved neutralizing action.